Librosa音頻處理（六）

劣質的麥克風在錄音時會把電流和嗡嗡的背景聲錄進去，通過對噪聲取樣去除頻率可以達到降噪的目的。

主要步驟：

1. 噪聲取樣

2. 統計頻率

3. 移除頻率

代碼如下：

'''採樣降噪'''
def test2(n, y, sr):

    indexs = librosa.effects.split(y, top_db=25-n)

    noicefrequencies = []
    for i in indexs:
        frequencies, D = librosa.ifgram(y[i[0]:i[1]], sr=sr, n_fft=22000)
        frequencies = frequencies.astype(int)
        noicefrequencies += frequencies.flatten().tolist()
    
    c = Counter(noicefrequencies)
    noicefrequencies = set(map(lambda x: x[0] // 2 * 2, c.most_common(400)))

    frequencies, D = librosa.ifgram(y, sr=sr)


    tempD = D.copy().astype(int)
    tempD = tempD // 2 * 2

    count = 0
    for i in range(D.shape[0]):
        for j in range(D.shape[1]):
            if tempD[i][j] in noicefrequencies:
                count += 1
                D[i][j] = 0
    print(count)
    return librosa.istft(D)